Constant-pressure combustion engine and method of operating same



B. BOLLI May 21 1929.

CONSTANT PRESSURE COMBUSTION ENGINE AND METHOD OF OPERATING SAME Filed March 31. 1926 Patented May 21 1929.

UNITED STATES v 1,714,210 PATENT. OFFICE.

BERNHARD BOLLI, OF ARBON, SWITZERLAND, AS SIGNOR TO THE FIRM: SOCIETE ANONYME ADOLPI-IE SAURER, 0F ARBON, SWITZERLAND, A SWISS CORPORATION.

CONSTANT-PRESSURE COMBUSTION ENGINE AND METHOD OF OPERATING SAME.

Application filed March 31, 1926, serial No. 98,802, and in Germany August 14, 1925.

In internal combustion engines of the eonstant-pressure-cycle or Diesel type, the regulation of the degree of admission will result in, that the average temperature or mean effective temperature during a cycle in the combustion space of the cylinder will be considerably decreased, if a condition of small load of some duration follows the condition of normal load. The same is true in the case of a zero load of some duration or a ermanent small load. The combustion, w ich is a good one during normal load will in this case. be impaired, so that a part of the injected fuel will deposit on the walls of the cylinder and the exhaust pipe. If thereupon the load is again increased, the temperature in the cylinder and in the discharge pipe will also increase, so that the deposited fuel will evaporate and cause the exhaust to become smoky. This will be the case especially in constant pressure combustion engines, which are operating under heavily fluctuating loads, such as is for instance the case with driving engines for motor cars.

This drawback is avoided according to this invention. According to this invention, during transit from a condition of normal load to some longer no-load condition or some longer operation under small load, either the quantity of the suction air is decreased according to the variation of the admission of the fuel, or else the exhaust gases are throt tled. Also according to the invention these procedures may be employed together for increasing the average temperature in the combustion space of the cylinder. Thedecrease of the quantity of suction air may be accomplished by various means, such as by throttling the suction air, shortening the stroke of the air admission valve, shortening the time during which the valve is open, heating the suction air, or by employing various combinations of these processes. The average temperature will thereby be raised to such an extent in the combustion s ace of the cylinder, that no more fuel can e deposited in the cylinder and in the discharge pipe, thereby rendering the exhaust also in case of smaller load and zero load free of smoke. The increase of temperature, which may be obtained by throttling the cold suction air or by heating the same is a cons uence of the fact that the quantity of air which is drawn into the combustion space and heated by the injected fuel under these conditions is smaller than the quantity of the charge, which corresponds to the normal admission.

Also by throttling the discharge of the exhaust gases, it will be possible to obtain an increase in the temperature, because more hot gases will remain asresidue in the cylinder by reason of the stowing u of the gases in front of the throttling va ve with resultant back pressure. The throttling of the exhaust gases may be brought about by various means such as by shortenin the stroke of the exhaust valve of the engine or by shortening the duration of opening of this valve. Preferably all these steps are applied simultaneously and to an extent which is determined by the quantity of surplus air necessary for a good combustion.

In case of heavily fluctuating operation of the engine, care'must be taken, that the temperature of the suction air will be enabled to quickly adapt itself to fluctuating operating vconditions, and means for this purpose are provided in accordance with this invention, as is hereinafter described.

In the accompanying drawing there is shown an example of carrying this invention into effect. In the constant-pressure combustion engine as shown in the drawing, there arranged a piston 1 within the cylinder 2 1n the ordinary manner, the fuel entering into said cylinder by means of a nozzle 3 and being injected into the air, which is heated above its temperature of ignition by compression. The cylinder head 4 carries the air admission valve 5 and the exhaust valve 6, which are controlled in the usual manner by means of a cam operated valve gear 7, 8, 9.

The suction conduit consists of a casing 10, which is provided with three extensions 11, 12, 13. The extension 11 serves for connecting the casing 10 to the suction channel 14, said latter channel being controlled b the valve 5. Through the extension 12, whic 1 leads to the outer air, cold air may be supplied to the channel 14. In this extension 12 100 is furthermore provided a throttle valve 15, which is controlled according to the charge or admission of the fuel.

For this purpose the admission lever 16 for controlling the degree of fuel admission of 105 the fuel pump 17, which is driven by the crank shaft 18, ispivoted by means of the guiding rod 19 to a lever 20 mounted on a shaft 21, by which a cam 22, which is carried by the shaft 21, may be adjusted. A 110 lever 24 is controlled by said cam, said lever carrying aroller 23 making a rolling contact with the surface of said cam. This lever 24 is connected with the throttle valve.

In the extension 13 of the casing there is also provided a throttle valve 25, which is controlled by the admission lever 16. For this purpose a lever 27 mounted on a shaft 28 is pivot-ally connected to the lever 20 by means of a guiding rod 26, said lever 27 serving for the adjustment of the cam 29, which is carried by the shaft 28. A lever 31 is controlled by this earn, a roller 30 being interposed between the cam surface and the lever. The lever 31 is connected with the throttle valve 25. Connected to the extension 13 of the casing 10 is a conduit 32, which is formed at its other end in the manner of a heating coil 33, whose orifice or intake is in connection with the exterior air. The coil 33 is positioned within the casing 34, into which the exhaust conduit 35 of the engine discharges. To the lower end of the casing 34 is connected a conduit 36, through which the exhaust gases are discharged from the casing 34. A throttle valve 43 is positioned in this conduit and likewise controlled by the admission lever 16. For this purpose a lever 38 is mounted upon the axis of rotation 37 of the admission lever 16, said lever 38 being pivotally connected to the lever 40 by means of a guiding rod 39. The lever 40 is mounted on a shaft which carries a cam 41, which serves for controlling a lever 44 by means of a roller 42 connected to said-lever. The lever 44 is connected with the throttle valve 43.

The operation of the constant-pressure combustion engine according to this invention is as follows.

During normal load of the engine, the throttle valve 25 is closed and the throttle valve 15, which is provided in the extension 12 of the casing 10 as Well as the throttle valve 37 in the exhaust conduit 36 are opened. The cold air for the combustion, which enters through the extension 12 of the casing 10, will now be supplied in such a quantity, that the fuel, which is injected through the nozzle 3 into the compressed air will undergo proper combustion, so that there will be no smoky exhaust gases discharging from the engine.

If now for instance in case of employing the engine as a driving engine for a motor car. the operation shall be changed over to a no-load operation of some longer duration. the admission of the cylinder 2 must be decreased. The admission lever 16 of the fuel pump 17 will thereby be rotated in acounterclockwise sense. In consequence thereof the throttle valve 15 will be completely closed by the mechanism 19,20, 22 and 24. The throttle valve 25 during adjustment of the admission lever 16 will first be entirely opened through the rods 26, 27, 29, and upon still further movement of the admission lever 16 with the decreasing admission of the fuel, the throttle valve 25 will be closed to a certain extent. Since the throttled air, which is drawn in through the extension 13 of the casing 10 must pass through the coil 33, which is heated by the hot exhaust gases of the engine, the air passing through the conduit 32 will be heated. Furthermore, the throttle valve 43 in the exhaust conduit 36 will be somewhat closed by the mechanism 38, 39, 40.

Instead of the cold air a definite reduced quantity of heated air will thereupon enter into the cylinder, said heated air bein more Furthermore, by reason of the stowing up of the exhaust gases in front of the throttle valve 43 during the exhaust stroke with resultant back pressure, there will remain more hotresidue gases in the cylinder 2, by reason of which the average temperature in the cylinder will also be increased. These two procedures willresult in that the temperature in the cylinder 2 and in the exhaust conduits 35, 36 will be so high, that also during no-load condition of the engine, no fuel will be able to deposit. which could produce a smoky exhaust, if the operation of the engine is again changed over from no-load condition to an operation with normal load. For this reversal to normal operation, the throttle valves 15 and 43 will come again into their open position by the adjustment of the admission lever 16, while t 1e throttle valve 25 will be closed.

If the operation at normal load shall be changed over to a permanent operation at small load, such as is for instance the case in a motor car, which travels for some longer time at low speed, the throttle valve 15 will be more or less closed according to the smaller adjustment of the admission lever 16, while the throttle valve 25 will be more or less opened. The cold air, which is drawn in through the extension 12 of the casing 10 will therefore be throttled, so that a smaller quantity of air corresponding to the temporary load will enter into the cylinder 2 during the suction stroke. while through the extension 13 of the casing 10 a corresponding quantitv of hot air will be added. In forming the cams 22 and 29 care is taken, that the throttled cold air and .the heated air, which are together entering in the extension 11 of the casing 10, are in such a ratio to each other, that for a quantity of fuel corresponding to the temporary load, the average temperature in the cylinder 2 will be of such a high value, that no fuel can deposit thereon.

It is thus seen that interconnections are provided between the fuel admission lever and the valve 15 in the unheated suction air intake, the valve 25 in the heated suction air intake, and the valve 43 in the exhaust (11$- 80 I highly heated up by the injected fuel.

charge passage. These interconnections are such that at normal or heavy loads when the fuel admission lever is correspondingly opened, the valve 15 in the unheated air intake. and the valve 43 in the exhaust passage are in open position, while the valve 25 in the heated air intake is closed. Further the construction of these interconnections is ,such that considerable variations in the degree of fuel admission by movement of the admission lever 16 can be effected without disturbing the normal positioning of these several valves.

As shown in the drawing, this is accomplished by the shape-of the several cams 22,

29' and 41. Thus the positioning of these valves at normal loads and heavy loads is not affected by the movement of the fuel admis sion control lever. However, when the degree of fuel admission has been decreased to a predetermined point corresponding to a position for small loads, the interconnection between the valves of the fuel admission lever 16 then becomes ell'ective to alter the respective positions of these valves upon further reduction in the degree of fuel admission.

I At a definite small load of the engine, the valve 15 commences to close, while the valve 25 will commence to open. Hot air is thus added to the suction air. Thereupon, upon further reduction of the load of the engine the valve 15 will be entirely closed and remain closed thereafter. The valve 25 in this case will completely open. The degree of throttling is in correspondence with the cross section of the two extensions 12 and 13 of the casing. Now, the throttling will begin to be effective, which is due to the fact, that the valve 25 upon further decrease in the degree of fuel admission will close to such an extent, that a smaller quantity of air for the combustion will pass into the cylinder 2.

During heavily fluctuating load, the normal quantity of cold combustion air or the uantity of heated air must be quickly introuced into the cylindcr2. After some longer operation at normal load the part 11 of the casing 10 is in comparatively cold condition, so that during changing over of the engine to no-load condition the heated air now entering will be subjected to an undesired cooling effect. In the same manner, upon changing the operation of the engine from a no-load. condition of some longer duration to a condition of normal load. the temperature of the cold air entering throughthe extension 11 of the casing 10v will be increased to an undesir- 1 extension 11. In consequence of the relatively short length of the extension 11 its capacity of storing up heat will be relatively small.

The desired increase of the average temperature in the combustion space of the cylinder 2 during operation of the engine in noload condition of some duration or during operation at a small load may of course also be attained by throttling the drawn in cold air by means of a throttle valve 15 or the like. Instead of providing a throttle valve in the suction conduit, the throttling may also be brought about by shortening the stroke of the admission or intake valve 5. Also a decrease of the admission of air will be attainable by shortening the time during which the intake or admission valve 5 is opened. The. shortening of the stroke of the valve or the shortening of the time, during which the valve is open, may be accomplished by means of any of the known adjustable valve gear mechanismsa The same holds true for the stowing up of the exhaust gases. which may be accomplished by shortening the stroke of the exhaust valve 6 or by shortening the time, during which this valve is open, both according to the degree of admission of fuel.

For changing over the condition ofthe engine to some longer no-load operation, there may alsobe employed, for instance, in case of cold weather, a further supplementary heating means 45, which is connected over a throttle valve 46, positioned in the pipe 47, I

with the suction pipe 10, 11, as indicated in dotted lines in the drawing.

Instead of employing .throttle Valves or socalled butterfly-valves, also other kinds of valves such as rotary valves, piston valves and the like may be employed for the regulation of the cross section of the several conduits.

I claim r 1. The method in the operation of an internal combustion engine of the constantpressure-cycle type having a cylinder enclosing a combustion space and working on combustion air and fuel injection, which com-- Y prises introducing heated combustion air into I the combustion space of said cylinder at small loads or zero load to increase the normal average temperature within the cylinder in order to prevent the depositing of fuel therein, and introducing unheated combustion air into said combustion space at heavier loads.

2. The method in the operation of an internal combustion engine of the constant- 1'n'essi1re-eycle type having a cylinder enclosing a combustion space and working on combustion air and fuel injection, which comprises heating the combustion air admitted.

into the combustion space of said cylinder at small loads to increase the normal average temperature within the combustion space in order to prevent the depositing of fuel therein, and throttling the admission of said heated air into the cylinder combustion space at still smaller loads to further increase the average temperature therein.

3. In an internal combustion engine of the" instant-pressure-cycle type working on combustion air and injection of fuel and having means for controlling the degree of fuel admission, the method in the operation thereof, which comprises decreasing the quantity of combustion air below the normal quantity introduced into the combustion space of said cylinder in accordance with variations in the degree of fuel admission at small loads or zero load in order to increase the normal average temperature within the combustion space to prevent the depositing of fuel therein, and admitting a normal quantity of combustion air into said combustion space irrespective of variations in the degree of fuel admission atlarger loads.

4. The method in the operation of an internal combustion engine of the constantpressure-cycle type having a cylinder enclosv therein.

ing a combustion space and working on combustion air and fuel injection, and having means fqr discharging the exhaust gases therefrom, which comprises throttling the discharge of the exhaust gases from said combustion space at small loads or zero load to thereby increase the normal average temperature within the combustion space in order to prevent the deposit of fuel therein, and per mitting unthrottled escape of the exhaust gases at loads within the normal heavier load range.

5. An internal combustion engine of the character described, comprising a cylinder, a piston therein, said parts enclosing a combustion space, means for injecting fuel into said combustion space, means for admitting combustion air into said combustion space, means for throttling the admission of said combustion air to' thereby increase the average temperature within said combustion space above the. normal average temperature produced therein, and means responsive to the load'on the engine for controlling the operation of said throttling mean's.

6. An internal combustion engine of the character described, comprising a cylinder, a'

piston therein, said parts enclosing a combustion space, means for injecting fuel into said combustion space, means for admitting combustion air into said combustion space, means for heating said combustion air and means for throttling the admission of the heated combustion air into said combustion space, said heating means and said throttling means being adapted to increase the average temperature within the combustion space above the normal average temperature produced 7. An internal combustion engine of the character described, comprising in combination, a cylinder, a piston therein, said parts enclosing a' combustion space, means for injecting fuel into said combustion space, means for controlling the degree of said fuel admission, means for admitting combustion air into said combustion space, means for increasing the average temperature within said combustion space above the average temperature normally produced therein, and control means for rendering said average temperature increasing means effective at small loads or zero load and for rendering the same ineffective at loads within the normal heavier load range.

8. An internal combustion engine of the character described, comprising in combination, a cylinder, a piston therein, said parts enclosing a combustion space, means for inj ecting fuel into said combustion space, means for admitting combustion air into said combustion space, an exhaust outlet passage for the discharge of exhaust gases from said combustion space, means Within said exhaust outlet passage for throttling the discharge of said exhaust gases to increase the average temperature within the combustion spaceabove the normal average temperature produced therein, and control means for rendering said ,throttling means effective at small loads or zero load and for rendering the same ineffective at loads within thenormal heavier load range.

9. An internal combustion engine of the character described, comprising in combination, a cylinder, a piston therein, said parts enclosing a combustion space, means for injecting fuel into said combustion space, means for varying the degree of said fuel admission, means for admitting combustion air into said combustion space, means for throttling the admission of said combustion air, and means for varying the throttling effect on said combustion air to reduce the quantity of combustion air'admitted in accordance with the reduction in the degree of fuel admission.

10. An internal combustion engine of the character described, comprising in combination, a cylinder, a piston therein, said parts enclosing a combustion space, a combustion air intake, a second combustion air intake, a heater positioned out of heat conducting relation' with said combustion space associated with one of-said combustion air intakes. and means for selectively controlling the flow through the said several combustion air intakes to control the heating of the combustion said combustion air intakes to control the lieatingof the combustion air admitted to said combustion'space as desired, and a common combustion air inlet passage of small heat cacylinder.

12. An internal combustion engine of the character described, comprising in combination, a cylinder,a piston therein, said parts enclosing a combustion space, a combustion air intake, a second combustion air intake, a heater associated with one of said combustion air intakes, a valve within each of said combustion air intakes, and an interconnection between said valves, constructed so that as one of saidvalves is moved toward opening position, the other of said valves is moved toward closing position, and so that one of said valves may be moved to throttle the introduction of combustion air passin through its associated passage when said ot er valve is in closed position.

13. 'An internal combustion engine of the character described, comprising in combination, a cylinder, apiston therein, said parts enclosing a combustion space, means-for injecting fuel int said combustion space,- means for' controlling the degree of said fuel admission, means'for admitting combustion air into said combustion space, means for heating said combustion air before introduction into said combustion space, control means for controlling the degree of heating of said combustion air, and an interconnection between said control means for the fuel admission and said control means for the heating of the combustion air for varying the degree of heating of said combustion air in accordance with the variation in the degree of fuel admission.

14. An internal combustion engine of the character described, comprisin in combination, a'cylinder, a piston therein, said parts enclosing a combustion space, a combustion air intake, a second combustion air intake, a heater associated with one of said combustion air intakes, means for varying the degree of fuel admission to said combustion space, valve means for controlling the flow of combustion air through said several combustion air intakes to control the degree of heating of the combustion air, and an interconnection between said fuel admission vary ing means and said valve means to control the degree of heating of the combustion air in accordance with the variation in the degree of fuel admission.

15. An internal combustion engine of the character described, comprising in combination, a cylinder, a piston therein, said parts enclosing a combustion space, a combustion air intake, a second combustion air intake, a heater associated with one of said combustion air intakes, means for varying the degree of fuel admission to said combustion space,

and means for closin the unheated combustion air intake and or opening the heated combustion air intake when the admission of fuel is reduced to a predetermined degree.

16. An internal combustion engine of the characterdescribed, comprising in combination, a cylinder, a piston therein, said partsenclosing a combination space, a combustion air intake, a second combustion air intake, a heater associated with one of said combustion air intakes, means for varying the degree of fuel admission to said combustion space, and means for closing the unheated combustion air intake and for opening the heated combustion air intake when the admission of fuel is reduced to a predetermined degree, said means being constructed to throttle the flow of combustion air through said heated combustion air intake upon still further reduction in the degree of admission of fuel.

17. An internal combustion engine of the character described, comprising in combination, a cylinder, a piston therein, said parts enclosing a combustion space, means for injecting fuel into said combustion space, means for controlling the degree of said fuel admis sion, a combustion air intake, a second combustion air intake, a heater associated with one-of said combustion air intakes, a valve within each of said combustion air intakes, and interconnections between said valves and said fuel admission varying means, said interconnections being so constructed that upon variation in the degree of fuel admission for moves toward closing position and the valve in the heated an intake moves toward open position until said first valve is fully closed and said second valve is fully opened, and upon still further reduction in the degree of fuel admission said valve in the heated air intake moves toward closing position while said valve in the unheated airintake remains closed.

18. An internal combustion engine of the character described, comprising in combina tion, a cylinder, a piston therein, said parts enclosing a combustion space, means for injecting fuel into said combustion space, means for admitting combustion air into said combustion space, means for throttling the admission of said combustion air, an exhaust passage for the discharge of exhaust gases from said combustion space, means for throttling the discharge of said exhaust gases, and an interconnection between said combustion air throttling means and said exhaust throttling means constructed to increase the throttling of said combustion air upon increase in the throttling of said exhaust gases.

19. An internal combustion engine of the character described, comprising in combination, a cylinder, a piston therein, said parts enclosing a combustion space, means for injecting fuel into said combustion space, means for admitting combustion air into said combustion space, means for heating said combustion air, means for varying the degree of the heating of said combustion air, an exhaust passage for the discharge of exhaust gases from said combustion space, means for throttling the discharge of said exhaust gases, and means for varying the degree of throttling of said exhaust gases, said parts being constructed to vary the degree of throttling of said exhaust gases in accordance with the variation in the degree of heating of said combustion air.

20. An internal combustion engine of the character described, comprising in combination, a cylinder, a piston therein, said parts enclosing a combustion space, means for iniecting fuel into said combustion space, means i for varying the degree of said fuel admission, means for admitting combustion air into said combustion space, means for throttling the admission of said combustion air, an exhaust passage for the discharge of exhaust gases from said combustion space, means for throttling the discharge of said exhaust gases, and interconnections between said several throttling varying means and said fuel admission varying means, sald nterconnections being so constructed as to 1ncrease the throttling of the admission of coinbustion air and the throttling of the discharge of exhaust gases in accordance with a vdecrease in the degree of admission of fuel.

21. An internal combustion engine otthe character described, comprising in combination, a cylinder, a piston therein, said parts enclosing a combustion space, means for mjecting fuel into said combustion space, a combustion air intake, a second combustion air intake, a heater associated with one of said combustion air intakes, valves within each of said combustion air intakes, an exhaust passage for discharging exhaust gases from said combustion space/,2: valve within said exhaust passage, and interconnections between said several valves constructed to vary the degree of throttling of said exhaust gases in accordance with the variation in the degree of heating of said combustion air.

22. An internal combustion engine of the character described, comprising in combination, a cylinder, a piston therein, said parts enclosing a combustion space, means for injecting fuel into said combustion space, means for controlling the degree of said fuel admission, a combustion air intake, at second combustion air intake, a heater associated with one of said combustion air intakes, valves within each of said combustion air intakes, an exhaust passage for discharging exhaust gases from said combustion space, a

valve within said exhaust passage, and interconnections between said several valves and said fuel admission controlling means constructed to eti'ect variations in the positioning of said several valves upon variation in the degree of fuel admission.

23. An internal combustion engine of the character described, comprising in combination,v a cylinder, a piston therein, said parts enclosing a combustion space, means for injecting fuel into said combustion space, means for controlling the degree of said fuel admission, a combustion air intake, a second combustion air intake, a heater associated with one of said combustion air intakes, valves within each of said combustion air intakes, an exhaust passage for discharging exhaust gases from said combustion space, a valve within said exhaust passage, and interconnections between said several valves and said fuel admission controlling means so constructed as to permit variations in the degree of fuel admission at normal loads and heavy loads without disturbing the positioning of said several valves, and to alter the positioning of said several valves upon variations in the degree of fuel admission at small loads or zero load.

24. In the operation of an internal combustion engine of the constant-pressure-cycle type working on combustion air and fuel injection, the method which comprises controlling the introduction of combustion air throughout,- a limited small load range to maintain throughout said small load range average temperatures within the combustion space of the engine above the temperature at which objectionable condensationof fuel results.

25. In the operation of an internal combustion engine of the constant-pressure-cycle type working on combustion air and fuel injection, the method which comprises coordinating the rate of introduction of combustion air and the temperature-at which the combustion air is introduced with engine load to maintain throughout a limited small load range average temperatures within the combustion space of the engine above the temperature at which objectionable condensation of fuel results.

26. In the operation of an internal combustion engine of the constant-pressure-cycle type working on combustion air and fuel injection, the method which comprises coordinating the rate of introduction of combustion air, the temperature at which the combustion air is introduced and the rate of escape of the exhaust gases with engine load to maintain throughout a limited small load range average temperatures within the combustion space of the cylinder of the en 'ine above the temperature at. which objectionable condensation of fuel results.

27. In the operationof an internal combustion engine of the constant pressure-cycle type working on combustion air and fuel injection, the method which comprises controlling the introduction of combustion air throughout a limited small load range to maintain within the combustion space of the cylinder of the engine average temperatures above the temperature atwhich objectionable condensation of fuel results,an'd introducing combustion air uncontrolled as to the condition thereof at loads within a heavier load range. 1

28. In the operation of an internal combustion engine of the constant-pressure-cycle type working on combustion air and fuel injection, the method which comprises coordinating the introduction of combustion air and the escape of products of combustion with engine load to maintain throughout a limited load range average temperatures within the combustion space of the cylinder of the engine above the temperature at which objectionable condensation of fuel results;

In testimony whereof I have afiixed my signature.

BERNHARD BOLLI. 

